1. Field of the Invention
The present invention relates to multistage switches. More specifically, the present invention relates to a multistage switch used for a shutter switch of a camera, a photographing switch of a video camera, a switch of other electronic apparatuses, etc., for providing a single switch with a plurality of operation instruction functions.
2. Description of Related Art
In the related art, multistage switches using disc springs have been generally known (see Japanese Unexamined Patent Application Publication No. 2000-57888). The multistage switches using disc springs function as multistage switches in which a switch push button is pressed by a user so that a plurality of disc springs provided in a multistage switch are sequentially deformed according to the pressing force with which the disc springs are pressed and the operating state of an electronic apparatus is sequentially switched.
The multistage switches of the related art using disc springs, etc., allow the operating state to be switched according to an amount by which a switch push button is pressed during the operation of the multistage switch. If a user desires to switch to the operating state of the first stage, the user may apply large force to the switch push button against the elastic force of the disc springs to switch to the operating state of the second or further stage. Thus, the user who wishes to obtain a desired operating state may not successfully obtain the desired operating state due to the mismatch between the user's feeling of operation and the actual operation of the multistage switch.
Specifically, a multistage switch used for a shutter of a camera typically has two operating stages, the first stage corresponding to the focusing operation and the second stage corresponding to the shutter release operation, i.e., the photographing operation. If the user fails to accurately press the switch push button, the shutter may often be released in an out-of-focus state.
Recently, in particular, with the reduction in size of cameras, there has also been a demand for a reduction in size of multistage switches, and a switch push button of a multistage switch is moved by a distance of approximately 2 mm from the state where no force is applied to the switch to the state where the shutter is released, i.e., the state of the second stage. The first stage corresponding to the focusing operation must be established within the distance of 2 mm. It is difficult for a general user to press the switch push button such a small distance and keep the focusing operation of the first stage against the pressure of the disc springs, and camera shake may be caused. Consequently, a problem of inaccurate focusing may arise.